Industrial control systems (ICS) are known that manage and control industrial and infrastructure systems (see Non-Patent Literature 1, for example). Many of conventional industrial control systems are not connected with an external network and operate with specific protocols. Recent industrial control systems, however, are increasingly connected with an external network through a generic protocol, such as the Internet protocol. This enables multiple industrial control systems to cooperate with each other.    [Patent Literature 1] National Publication of International Patent Application No. 2007-506353    [Non-Patent Literature 1] “SCADA”, (online), Wikipedia, (searched on Mar. 30, 2011), the Internet, URL: http://ja.wikipedia.org/wiki/SCADA